The present invention relates to a method for the monolithic fabrication of the front face of an optoelectronic and/or optical couplers, and it relates, more particularly, to the fabrication of such coupler components including waveguide structures.
For the efficient production of optical elements and optoelectronic semiconductor elements, it is common to fabricate as large a number of identical elements as possible on a small sheet (wafer or chip) of a suitable material, for example semiconductor material or lithium niobate (LiNbO.sub.3), is required. In the case of edge-emitting ridge waveguides, such as for example MCRW (metal cladded ridge waveguide) laser diodes, this requires that all technology steps should be carried out on the wafer of semiconductor material. Among them is also the complex procedure for the manufacture of the emitting edges such as, for example, of the laser mirrors, and in particular of the ridge waveguide itself.
This problem could until now not be solved by using a monolithic technology approach, since with conventional technologies for the manufacture of such elements always produces unintentional malformation at the light-emitting edges or mirrors of the components which made regular operation and achievement of an acceptable yield very difficult or impossible. For this reason the light-emitting edges of ridge waveguides were until now manufactured by fracturing along the (material specific) crystal axis suitable for this purpose.
In the meantime, it has become possible to realize laser diodes in monolithic technology on a semiconductor wafer. To manufacture the plane parallel end faces (laser mirror) functioning as a laser resonator, the semiconductor surface to be protected is covered with a photo lacquer of the desired geometric structure. Through a dry etching process, the desired mirror structure is subsequently obtained on the semiconductor wafer with the side walls of the etching grooves produced forming partially the edge-emitting areas or laser mirrors.